Summary
In 1997, Papa and Adams developed a model for optimizing detention pond geometry to minimize SWM pond costs. Decision variables in this model included storage volume, controlled release rate, and pond depth. Constraints included pollution control and runoff control.
In this article, Behera, Papa, and Adams extend their work to a system of three parallel catchments using dynamic programming. In this context, the objective function is expanded to minimize the total cost of implementing all three SWM ponds in the system. The authors define pond cost as the opportunity cost of the land occupied by the pond plus the construction and operation, maintenance, and repair (OMR) costs associated with the pond. The constraints are similarly expanded - the overall pollution control from the system prior to discharge must achieve a minimum specified level of control, and the runoff control from the system must also achieve a minimum specified level of control. Runoff and pollution control performances are defined by complex "isoquant" equations involving the runoff coefficient, rainfall event duration, rainfall event volume, and interevent time.
The authors go on to present the results of their dynamic program, and conclude the paper by discussing its benefits to land developers and municipalities. They also note that although the article only discussed a simple system of three catchments, their method is general, and may be applied to more complex urban runoff systems.
Discussion
From an economic perspective, I think the author's work is very valuable. I have always thought of detention ponds on a site-by-site basis, so the idea of analyzing several as a system struck me as creative. I can see land developers being particularly interested in this research, since the methodology reveals savings which were previously unachievable.
While their economic analysis was good, I feel that the authors overlooked a major trend in detention pond design. Today there is a large focus on seamlessly integrating detention ponds with their surrounding environment. When executed properly, the space can be used for other purposes during times of little or no storage, and oftentimes the public isn't even aware that the space is a detention facility at all. While the authors' model may yield the most economical solution, I doubt that it would be a seamless one.
The article also made me wonder how the model would change over time. While one solution may be optimal today with X number of detention ponds, future development will change the solution when more detention ponds are present in the model. Since the original detention ponds are already built to the specifications of the original solution, however, it seems that one would have to settle for a suboptimal solution when designing future development.
In this article, Behera, Papa, and Adams extend their work to a system of three parallel catchments using dynamic programming. In this context, the objective function is expanded to minimize the total cost of implementing all three SWM ponds in the system. The authors define pond cost as the opportunity cost of the land occupied by the pond plus the construction and operation, maintenance, and repair (OMR) costs associated with the pond. The constraints are similarly expanded - the overall pollution control from the system prior to discharge must achieve a minimum specified level of control, and the runoff control from the system must also achieve a minimum specified level of control. Runoff and pollution control performances are defined by complex "isoquant" equations involving the runoff coefficient, rainfall event duration, rainfall event volume, and interevent time.
The authors go on to present the results of their dynamic program, and conclude the paper by discussing its benefits to land developers and municipalities. They also note that although the article only discussed a simple system of three catchments, their method is general, and may be applied to more complex urban runoff systems.
Discussion
From an economic perspective, I think the author's work is very valuable. I have always thought of detention ponds on a site-by-site basis, so the idea of analyzing several as a system struck me as creative. I can see land developers being particularly interested in this research, since the methodology reveals savings which were previously unachievable.
While their economic analysis was good, I feel that the authors overlooked a major trend in detention pond design. Today there is a large focus on seamlessly integrating detention ponds with their surrounding environment. When executed properly, the space can be used for other purposes during times of little or no storage, and oftentimes the public isn't even aware that the space is a detention facility at all. While the authors' model may yield the most economical solution, I doubt that it would be a seamless one.
The article also made me wonder how the model would change over time. While one solution may be optimal today with X number of detention ponds, future development will change the solution when more detention ponds are present in the model. Since the original detention ponds are already built to the specifications of the original solution, however, it seems that one would have to settle for a suboptimal solution when designing future development.
3 comments:
I agree. Good job Ian. Keep up the good work.
P.S. I called it Blog 6 because it is the sixth blog... and it was late and I am lazy. I'll try to be more creative next time.
It is kind of like a tradition to approach these problems as stand-alone objects rather than interactive components of a complex system. Isolating the detention pond system would certainly have made the model delineation an easier task because that way, we would have to deal with fewer parameters. I'm not saying that every model has to be complex, but rather should be developed at a need-based criteria.
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